In 2020 and 2021, the Census Bureau released several data products meant to demonstrate the effect of the Bureau’s new Disclosure Avoidance System (DAS) on population counts (using 2010 census data). The final demonstration product using the same privacy parameters applied to the 2020 census data was released in June 2021. The University of Minnesota’s IPUMS National Historical Geographic Information System (NHGIS) volunteered to convert the Census Bureau’s un-tabulated demonstration data into useful summary formats, linked to the published 2010 summary data. The intent of both organizations was for census data users to use these tabulated files to assess the impact of the DAS on their own local data. NHGIS tabulated data is located here. Information on the DAS is located here.
The mean absolute change in population between the published 2010 data and the demonstration product data is -0.3 people. The largest absolute change in population between the two files is for Chicago with an increase of 31 people in the demonstration data. The mean percent change in population for all Cook County towns is 0.007%. There are 0 towns with a percent change in total population of more than 5%. The town with the largest percent change in the demonstration total population counts is Bedford Park with a percent change of 0.52%. These patterns are reflected in the box plots below.
Conclusions: Total municipality populations are unlikely to be largely impacted by the 2020 DAS parameters and can be used without reservation.
The mean absolute change in the Hispanic/Latino population by municipality between the published 2010 data and the demonstration product data is -0.12 people. The largest absolute change in population between the two files is for Chicago with a decrease of 197 people in the demonstration data. The mean percent change in the Hispanic/Latino population for all Cook County towns is -0.48%. There are 13 towns with a percent change in the Hispanic/Latino population of more than 5%. The town with the largest percent change in the demonstration Hispanic/Latino population counts is Robbins with a percent change of -28.6%. The median percent change is 0% and the interquartile range is [-1.04%, 0.82%]. The number of outliers and IQR varies by public health district.
Conclusions: When aggregated, the variation introduced by the DAS settings for the Hispanic population at the municipal level largely balances out. This means we can be reasonably confident in the 2020 jurisdiction-level Hispanic/Latino population estimate, as calculated by the subtraction method. However, at the individual municipality level, while the majority of towns are within acceptable bounds for percent change, outliers do exist - some with very high levels of distortion. Outliers are more prevalent in areas where the Hispanic/Latino population is low. Calculation of rates for the Hispanic/Latino population at the municipal level should be avoided for the North and South District and must be accompanied by data caveats if performed. Alternatively, a minimum population threshold of 500 or 1000 could be applied, below which rates would be censored.
| Municipality | Published Total | Published H/L | Demonstration H/L | Percent Change |
|---|---|---|---|---|
| Robbins | 5337 | 175 | 125 | -28.57 |
| Phoenix | 1964 | 116 | 102 | -12.07 |
| Barrington Hills | 4209 | 114 | 102 | -10.53 |
| Matteson | 19009 | 813 | 749 | -7.87 |
| Kenilworth | 2513 | 41 | 38 | -7.32 |
| Deer Park | 3200 | 110 | 102 | -7.27 |
| Ford Heights | 2763 | 42 | 39 | -7.14 |
| South Barrington | 4565 | 118 | 110 | -6.78 |
| Lincolnwood | 12590 | 859 | 810 | -5.70 |
| Richton Park | 13646 | 477 | 501 | 5.03 |
| Winnetka | 12187 | 271 | 291 | 7.38 |
| Northfield | 5420 | 159 | 171 | 7.55 |
| Inverness | 7399 | 178 | 197 | 10.67 |
The mean absolute change in the non-Hispanic Black or African American population by municipality between the published 2010 data and the demonstration product data is 2.8 people. The largest absolute change in population between the two files is for Chicago with an increase of 90 people in the demonstration data. The mean percent change in the non-Hispanic Black population for all Cook County towns is -1.38%. There are 25 towns with a percent change in the non-Hispanic Black population of more than 5%. The town with the largest percent change in the demonstration population data is Forest View with a percent change of -40%. The median percent change is 0% and the interquartile range is [-1.58%, 0.47%]. The number of outliers and IQR varies by public health district.
Conclusions: When aggregated, the variation introduced by the DAS settings for the non-Hispanic Black population at the municipal level, though larger than for the Hispanic population, largely balances out. This means we can be reasonably confident in the 2020 jurisdiction-level non-Hispanic Black population estimate, as calculated by the subtraction method. However, at the individual municipality level, close to 1 in 5 towns have percent changes in population outside acceptable bounds. As expected, outliers are more common in areas where the non-Hispanic Black population is low. Calculation of rates for the non-Hispanic Black population at the municipal level should be advised against for towns outside of the South District. When rates must be calculated, strong data caveats should be included. Alternatively, a minimum population threshold of 500 or 1000 could be applied, below which rates would be censored.
| Municipality | Published Total | Published NHB | Demonstration NHB | Percent Change |
|---|---|---|---|---|
| Forest View | 698 | 5 | 3 | -40.00 |
| Golf | 500 | 3 | 2 | -33.33 |
| Bedford Park | 580 | 4 | 3 | -25.00 |
| Palos Park | 4847 | 36 | 29 | -19.44 |
| Winnetka | 12187 | 31 | 25 | -19.35 |
| Harwood Heights | 8612 | 53 | 44 | -16.98 |
| Hodgkins | 1897 | 6 | 5 | -16.67 |
| Riverwoods | 3660 | 26 | 22 | -15.38 |
| Lincolnwood | 12590 | 129 | 111 | -13.95 |
| Inverness | 7399 | 36 | 31 | -13.89 |
| Park Ridge | 37480 | 168 | 145 | -13.69 |
| Hometown | 4349 | 38 | 34 | -10.53 |
| Lemont | 16000 | 58 | 53 | -8.62 |
| Deerfield | 18225 | 93 | 85 | -8.60 |
| Northfield | 5420 | 26 | 24 | -7.69 |
| Riverside | 8875 | 110 | 103 | -6.36 |
| Palos Heights | 12515 | 208 | 197 | -5.29 |
| Countryside | 5895 | 179 | 189 | 5.59 |
| Franklin Park | 18333 | 167 | 178 | 6.59 |
| Willow Springs | 5524 | 56 | 61 | 8.93 |
| Western Springs | 12975 | 43 | 48 | 11.63 |
| Deer Park | 3200 | 28 | 32 | 14.29 |
| Kenilworth | 2513 | 7 | 8 | 14.29 |
| Barrington | 10327 | 96 | 110 | 14.58 |
| Barrington Hills | 4209 | 32 | 40 | 25.00 |
The mean absolute change in the non-Hispanic Asian population by municipality between the published 2010 data and the demonstration product data is 0.23 people. The largest absolute change in population between the two files is for Skokie with an increase of 60 people in the demonstration data. The mean percent change in the non-Hispanic Asian population for all Cook County towns is 1.59%. There are 33 towns with a percent change in the non-Hispanic Asian population of more than 5%. The town with the largest percent change in the non-Hispanic Asian demonstration data is Hodgkins with a percent change of 100%. The median percent change is 0% and the interquartile range is [-1.77%, 1.12%]. The number of outliers and IQR varies by public health district.
Conclusions: When aggregated, the variation introduced by the DAS settings for the non-Hispanic Asian population at the municipal level, though larger than for the Hispanic population, largely balances out. This means we can be reasonably confident in the 2020 jurisdiction-level non-Hispanic Asian population estimate, as calculated by the subtraction method. However, at the individual municipality level, over 20% of towns have percent changes in population outside acceptable bounds. Outliers are present in all public health districts but distortions are particularly high in the South. Calculation of rates for the non-Hispanic Asian population at the municipal level should be avoided whenever possible. When rates must be calculated, strong data caveats should be included. Alternatively, a minimum population threshold of 500 or 1000 could be applied, below which rates would be censored.
| Municipality | Published Total | Published NHA | Demonstration NHA | Percent Change |
|---|---|---|---|---|
| Calumet Park | 7835 | 24 | 3 | -87.50 |
| Barrington Hills | 4209 | 272 | 239 | -12.13 |
| East Dundee | 2860 | 76 | 68 | -10.53 |
| Posen | 5987 | 20 | 18 | -10.00 |
| Crestwood | 10950 | 105 | 95 | -9.52 |
| Steger | 9570 | 96 | 87 | -9.38 |
| Dolton | 23153 | 68 | 62 | -8.82 |
| Riverside | 8875 | 184 | 168 | -8.70 |
| Hometown | 4349 | 14 | 13 | -7.14 |
| Golf | 500 | 15 | 14 | -6.67 |
| Hazel Crest | 14100 | 91 | 85 | -6.59 |
| Calumet City | 37042 | 108 | 101 | -6.48 |
| Kenilworth | 2513 | 33 | 31 | -6.06 |
| Deer Park | 3200 | 136 | 128 | -5.88 |
| Countryside | 5895 | 86 | 81 | -5.81 |
| Western Springs | 12975 | 179 | 170 | -5.03 |
| North Riverside | 6672 | 137 | 144 | 5.11 |
| Matteson | 19009 | 187 | 197 | 5.35 |
| Park Forest | 21975 | 157 | 167 | 6.37 |
| Country Club Hills | 16541 | 162 | 174 | 7.41 |
| Blue Island | 23706 | 79 | 85 | 7.59 |
| Chicago Heights | 30276 | 87 | 95 | 9.20 |
| Glenwood | 8969 | 27 | 30 | 11.11 |
| Palos Park | 4847 | 82 | 94 | 14.63 |
| Riverdale | 13549 | 13 | 15 | 15.38 |
| Merrionette Park | 1900 | 19 | 22 | 15.79 |
| Thornton | 2338 | 16 | 19 | 18.75 |
| Burnham | 4206 | 21 | 27 | 28.57 |
| South Chicago Heights | 4139 | 46 | 61 | 32.61 |
| Forest View | 698 | 13 | 19 | 46.15 |
| Dixmoor | 3644 | 2 | 3 | 50.00 |
| Ford Heights | 2763 | 3 | 5 | 66.67 |
| Hodgkins | 1897 | 2 | 4 | 100.00 |
Based on the analyses above, individual municipalities may have race and ethnicity population estimates with significant distortion, but these distortions balance each other out when municipalities are aggregated to create jurisdiction level population estimates. CCDPH public health districts are also aggregations of municipalities. The table below displays the percent change in each type of population estimate at the district level.
Conclusions: When aggregated, the variation introduced by the DAS settings balances out for both total and all racial/ethnic population estimates. District-level population estimates can be used without reservation.
| District | Total | Hispanic | Non-Hispanic Black | Non-Hispanic Asian |
|---|---|---|---|---|
| North | 0% | -0.03% | 0.21% | 0.01% |
| South | 0% | -0.06% | 0.11% | 1.26% |
| Southwest | -0.01% | 0.22% | -0.25% | -0.23% |
| West | 0% | 0.01% | -0.03% | -0.31% |